1. Field of the Invention
This invention relates to an ankylosis type artificial tooth root of a dual structure in which the function of a periodontal membrane (periodontal ligament) is assumed by a buffer material.
2. Description of the Prior Art
It has long been practiced to have a device implanted directly in a jaw bone, in place of a denture, as a dental implant in order to replace a lost tooth. However, there is much to be desired in technical aspects and in respect of characteristics of the implant material.
For example, an artificial tooth root of bioactive ceramics or titanium in current use is not provided with an effective shock-absorbing or buffering mechanism because its connection with the jaw bone is via ankylosis or osseointegration. However, an ankylosis type tooth is found only in lower animals, such as reptiles, and not in higher animals. Therefore, an effective shock-absorbing mechanism needs to be devised in order to utilize it for a human.
That is, teeth of a mammal are required to have minor mobility in order to accommodate chewing, i.e, mastication. Thus the teeth of a mammal is connected by gomphosis to a jaw bone. On the other hand, ankylosis type teeth are characteristic of a reptile which cannot chew, and are necessarily fractured, so that, with certain reptiles, teeth are renewed 20 to 30 times. As a matter of fact, an artificial tooth root of a man, affixed to bone, is broken in many cases, if the tooth root is formed of ceramics. With an implant of a time-honored shape, a fibrous tissue having a function similar to the periodontal membrane is not produced because of its inadequate shape, even although it is made of a metallic material. As a result, the tooth root is occasionally fractured and, in a majority of cases, the bone tissue around the root is also broken.
The present invention provides an ankylosis type artificial tooth root in which the function of the periodontal membrane is taken over by a dual structure buffer material. The buffer material functions as transforming means for the principal stress trajectory, while the outer root of the artificial tooth root is equivalent to an alveolar bone formed around the inherent tooth root. In this manner, stable renewal and remodeling of bone around the artificial tooth root may be maintained for a prolonged time under maintenance of the chewing function.